This invention relates to welding generally, and particularly to welding by heat produced by laser radiation.
It is well known that high reflectivity materials are particularly difficult to weld when using a laser as the source of welding heat. Laser radiation occurs in the visible and near-visible regions of the spectrum and, therefore, such radiation is easily reflected by a highly reflective surface and will not penetrate sufficiently deep enough to produce a weld. Application of a low reflection coating has been previously suggested as a technique for improving energy absorption but will not generally improve weldability. This is due to the fact that such coatings are vaporized during the initial impact of the laser beam upon the coating.
Plated, evaporated or electrodeposited coatings have proven to be of very limited value since practical limitations on such coating thicknesses are on the order of about 0.0005 inch (about 0.0127 millimeters).